Yes it is possible to make a Survey123 survey public and this will enable users to submit data anonymously (no login required) - this works via the field app or web app. Please see: Share survey—Survey123 for ArcGIS | ArcGIS

Yes it is possible to make a Survey123 survey public and this will enable users to submit data anonymously (no login required) - this works via the field app or web app. Please see: Share survey—Survey123 for ArcGIS | ArcGIS